I did all my artwork on an HP 8550, but the resulting prints have a very "matte" look to them. I wanted to use an inkjet on photo paper, but it was clear very soon that would have killed many ink cartridges.
For something as permanent as side art, I'd go with having one of the pros print it on vinyl. The color laser print, though, is fine for things you may change, like a control panel overlay (#3 for me) or marquee (#2 for me) that are going to be covered by plexi (for both protection and gloss).
Also remember that side art size prints will take a LOT of toner, and color toner is expensive. If this printer is at work (who has one of these at home?) and they're metering usage, you could get an ugly suprise...
--Chris